Report

FZJ-2016-05732

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Ein neues Verfahren zur präzisen Messung der metallischen Wärmeleitfähigkeit bei normalen und hohen Temperaturen

Binkele, L. (Corresponding author)FZJ*

1990
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/12647

Report No.: Juel-2379

Abstract: Theoretical and experimental investigations on a new measuring technique are described ; a technique similar to the well knownKohlrausch measuring technique, which is characterized by direct electrical sample heating . Subject of the investigations is acylindrical metallic sample, 5 mm thick and 200 mm in length, which is positioned vertically between water-cooled clamps in a vacuum container. The sample can be heated using two simultaneously operating current sources, a 50 Hz-source for axial flow (main heating) as well as a 200 kHz-induction source for generating eddy currents in two short regions above and below the sample centre (additional heating). By using two heating sources different symmetrical temperature profiles in a central eddy-current-free area of about $\pm$ 10 mm can be produced for any given central sample temperature. Using a one-dimensional theory and some simplified assumptions (constant conductivities and temperature-linear radiation heat loss over a small temperature span of typically 10 degrees) it can be shown that the different profiles are of the cosh-type. By cutting the infinite series of the cosh-function an explicitexpression for the thermal conductivity can be determined. The formula combines measuring data characteristic of different profiles, namely 50 Hz currents and voltages as well as temperatures in three central sample points. Thermal conductivity values measured by using this simplified theory must be erroneous. Therefore in a further chapter a more extensive mathematical treatment is given to make the calculation of theoretical systematic errors possible. The results calculated for numerous pure metals by the use of an IBM-computer indicate that certain parameters like the sample thickness, the length of central sample portion as well as the curvature of the coshprofiles normally can be chosen in such a manner that the total error of a measured conductivity value is dominated byuncertainties of measuring quantities but not by the use of the simplified theory. [...]

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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